Fig. 5. Representative recordings of I^toin (A ) subendocardial (ENDO) and (B ) subepicardial (EPI) cells during control conditions and after a 1-min exposure to 0.6 mm halothane. Currents were measured with the whole cell patch clamp technique as described by Davies et al. , 21with 20 μm CdCl²used to block I^Ca. I^towas evoked by 200-ms voltage clamp pulses to +60 mV from a holding potential of −80 mV.